Awesome color spectrum Scott. The clear to opalized transition is a bit like magic. Would be great for live demos. I had a show this weekend and all the customers were drawn to these pieces. Inside of a conch shell will be a great application.

A bunch of boro artists came by and suggested that it looked just like "amber purple" in the COE 33 world.

The matte finish suggested by Sky on my other thread was pretty damn amazing. I didn't think it could look better but I have to admit that I like it even better.

Actually, this not a hard glass. It does depend on the basic clear formulation. It would probably be equally relevant if I had a class on clear bases for colors but it is not sexy. In all my correspondence with John we talk base glasses more than anything. I don;t think anyone pays a whit of attention to those basics. I think I have five bases and John, last time I checked, has nine.

Once through the base, then apply the rules for expansion and viscosity. Make it fit.

Been working with the cullet formula for a while now. I'm trying to achieve more of the blue, lavender, red colors and less yellow-brown. I've recently tried 5g cinnabar in an 8lb mix of the normal chalcedony formula (no cobalt or copper) from Pete with no obvious benefits. I realize cullet could be my limiting factor and that whatever reduction state is needed for the "lovely" colors may be limited in an oxidized base glass. My ventures into batch are awaiting the availability of the commercial batch guys.

I did run across an interesting excerpt from Charles Bray in his "Dictionary of Glass" while looking up the possible effects of mercury in glass. I don't have the book (yet)....this came up in the eBook preview from Google.

from page 102...Into this was added a mixture of zaffre (a type of cobalt silica), iron oxide, copper oxide and mercury sulphide dissolved in nitric acid. The resulting glass was worked at the furnace in the normal way, but in common with some coloured glasses such as copper, gold and selenium rubies, it was necessary to get the colour to strike. When ware for such glasses are made the metallic crystals formed during the initial cooling are very small but reheating at the glory hole can be...

I can't wait to get the book and read the context and conclusion of this paragraph. Based on this, perhaps the cinnabar requires pretreatment with nitric acid...pretty nasty. The info I have read suggests this requires boiling temps on top of the already dangerous chemicals involved. OR...they are just dissolving everything in acid and the only benefit is to create silver nitrate. Any thoughts?

I'll have to give the cobalt salts a try...only ever used oxide form. I'd like to maximize the amount of black tin for use in cullet. Also, in looking back at the original recipe you mentioned using window glass with a relatively high iron content. I'm going to try and find the optimal iron content for cristalica. It has seemed to help to bump up both the black tin and red iron in my preliminary deviations from the original. Some have mentioned sugar as an alternative reducing agent. Lots to try...just wish I had a couple more color pots.

If you push the iron too hard, it won't opalize. Sugar doesn't really work unless it's very short term with gas. Black tin is really the reducing agent of choice. The Mercury really is an unknown for me.

I've eliminated the zinc with no change. I was trying to remove some of the off-white, yellow to beige opals but they still develop. The tin seems to push toward the purples, greens and blues. Wish it wasn't so pricey. I'll also try less silver. The reds in these photo are what I'd like to achieve. I sure didn't see anything start to pop out with mercury, but I'm far from exhausting the possibilities with it.

It comes from red copper. Run your annealer hot. It will strike there. We periodically threw small wax balls onto the pot surface before the slap gather, sometimes we used an oxy acety;ene torch briefly on the surface. Don't gather, slap.

Thanks Pete. I'll give it a shot. My color pots gather vertically which works nicely for the colloid formation. The hotter anneal is going to be interesting...I recall Jordan Kube also saying the red copper strikes in the annealer. I'll bump it up 50 degrees or so.

Don't forget, process plays an important role in color formation. When I slap a large gather of chalcedony on the marver and pick it up on the side of a solid piece of clear to sculpt, it's nothing like blowing. I would go so far as to say it's an apples to oranges comparison. They've found that color formation in these types of silver glasses depends not only on the size of particle but also the shape. Good luck getting a handle on that! I'd love the hear about your good results though. I'm on the same path right now but with nothing significant to report.

I've found I can get Dino like results with the process I described. Doesn't look exactly like his but I've never been able to touch these colors blowing. I would stay away from mercury. There's a reason nobody uses it.

I've ordered some more of it on ebay. It's the only place I've found...straight from Hong Kong. Reasonably priced.

The results from Josh Simpson and Pete are mostly blown. Dino does some bowls also with nice color results. That pink-lavender-red transition is my goal, currently. I start my day with a little solid work just to see the look of the glass. I agree that it likes to be thick. However, I did make some ornaments for co-workers and they looked pretty nice aside from the tiny pin needles which only I seemed to notice.

saying "it likes to be thick is another way of saying, "It likes to be cooled slowly". Think on that.
Then Think on the notion that I don't think anyone's holding out on you. They;re saying there's a lot of stuff that hasn't been done. Some will be crap, some may not be.

This has been going on for four thousand years. Think on that. You have giants around you. You need to add to the knowledge.

My understanding of Mercury is that it is WAY more toxic than most things, particularly vaporized.

Be damn sure your ventilation is up to it if you choose to use it.

Years ago people were experimenting with Mercury as a weight shifting mechanism in stock car racing. It was banned on the premise that if a few drops of Mercury found their way onto the hot manifold in a wreck the vapor could be fatal to anyone nearby.

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